Which founding Beach Boy was the Wilson brothers' cousin?

Mike Love was the founding Beach Boy who was the Wilson brothers' cousin.

Love joined Brian, Dennis, and Carl Wilson in the musical group that became the Beach Boys. He encountered the Wilsons at family gatherings, where Brian's vocal arrangements and the family's shared interest in harmony helped lay the groundwork for the band's sound.

The original lineup therefore combined three brothers with two close connections: Love, their cousin, and Al Jardine, Brian's school friend. Love was an important early vocalist and co-writer of “Surfin'” with Brian Wilson, the first single associated with the group.

A common mix-up is to identify David Marks or Bruce Johnston as founders because both became significant Beach Boys musicians. Marks joined the early touring and recording lineup after Jardine's temporary departure, while Johnston joined later as a touring replacement for Brian. Neither was part of the original five-member founding group.